The present invention relates generally to an apparatus for protecting building occupants from injury caused by flying debris from a window as a result of an explosion or the like. More particularly, it relates to such an apparatus wherein a gas generator or similar device is used to close a louver system to form a protective barrier adjacent the window before an explosion causes it to disintegrate.
Terrorist bomb attacks provide a demonstrable need for increased protection for building occupants from the debris hazards generated by the blast. Loss of life in such attacks is caused mainly by the debris hazard generated by the blast., e.g., debris from the breakup of windows, cladding and ceiling and room fixtures. While debris hazards can be mitigated by the use of increased standoff, air blast barriers, stronger cladding and windows, and window coatings, such devices merely reduce but do not totally eliminate personnel injury, and, in many cases are difficult and/or expensive to install.
Accordingly, a need has arisen for a simple and effective apparatus that provides a xe2x80x9clast line of defensexe2x80x9d for the occupants of a building subjected to an explosion and prevents or significantly reduces injury to the occupants from flying debris from windows or the like. The window protection apparatus of the present invention fills this need and is not subject to any of the disadvantages of previously used systems.
In the apparatus of the present invention, a louver system is mounted adjacent to the inside and/or outside of a window and is constructed of strong, flexible slats which are normally in the open, generally horizontal position. Upon detection of an explosion or the like, the louvers are rapidly rotated to the closed, generally vertical position and are interlocked to either reduce the blast pressure on the window and cladding from the outside or to prevent propagation of window shards or debris into the room from the inside. Because of the interlocking of the slats, they are maintained in the closed position when the louver system is deflected inwardly by the bomb blast to protect the occupants from injury by flying debris from the window.
To reinforce the louver system during inward deflection by an explosion or the like, a plurality of generally vertically extending, high strength, high elongation cables or straps are mounted adjacent the interior surface of the louver system and are attached to the adjacent portions of the floor and ceiling to react to the resultant pressure loads on the louver system and translate these loads into in-plane floor or ceiling loads. The cables may be connected to a suitable shock absorbing system in the floor and/or ceiling to preclude failures associated with exceptionally high strain rate effects caused by the blast loads and to allow the cables to displace inwardly to reduce the out-of-plane floor or ceiling loads.
A pyrotechnically generated gas system may be used to rapidly rotate the louvers to the closed position before the window is subjected to the bomb blast. In operation, a sensor may be located remote from the window and is connected to the gas generating system to activate it upon the sensing of an explosion or the like.